Cancer is a generic name for a wide range of cellular malignancies characterized by unregulated growth, lack of differentiation, and the ability to invade local tissues and metastasize. These neoplastic malignancies affect, with various degrees of prevalence, every tissue and organ in the body.
A multitude of therapeutic agents have been developed over the past few decades for the treatment of various types of cancer. The most commonly used types of anticancer agents include: DNA-alkylating agents (e.g., cyclophosphamide, ifosfamide), anti-metabolites (e.g., methotrexate, a folate antagonist, and 5-fluorouracil, a pyrimidine antagonist), microtubule disrupters (e.g., vincristine, vinblastine, paclitaxel), DNA intercalators (e.g., doxorubicin, daunomycin, cisplatin), and hormone therapy (e.g., tamoxifen, flutamide).
Colorectal cancer is among the leading causes of cancer-related morbidity and mortality in the U.S. Treatment of this cancer depends largely on the size, location and stage of the tumor, whether the malignancy has spread to other parts of the body (metastasis), and on the patient's general state of health. Options include surgical removal of tumors for early stage localized disease, chemotherapy and radiotherapy. However, chemotherapy is currently the only treatment for metastatic disease. 5-fluorouracil is currently the most effective single-agent treatment for advanced colorectal cancer, with response rates of about 10%. Additionally, new agents such as the topoisomerase I inhibitor irinotecan (CPT11), the platinum-based cytotoxic agent oxaliplatin (e.g. ELOXATIN™), and the EGFR kinase inhibitor erlotinib ([6,7-bis(2-methoxyethoxy)-4-quinazolin-4-yl]-(3-ethynylphenyl)amine, e.g. erlotinib HCl, TARCEVA™) have shown promise in treatment.
Over-expression of the epidermal growth factor receptor (EGFR) kinase, or its ligand TGF-alpha, is frequently associated with many cancers, including breast, lung, colorectal and head and neck cancers (Salomon D. S., et al. (1995) Crit. Rev. Oncol. Hematol. 19:183-232; Wells, A. (2000) Signal, 1:4-11), and is believed to contribute to the malignant growth of these tumors. A specific deletion-mutation in the EGFR gene has also been found to increase cellular tumorigenicity (Halatsch, M-E. et al. (2000) J. Neurosurg. 92:297-305; Archer, G. E. et al. (1999) Clin. Cancer Res. 5:2646-2652). Activation of EGFR stimulated signaling pathways promote multiple processes that are potentially cancer-promoting, e.g. proliferation, angiogenesis, cell motility and invasion, decreased apoptosis and induction of drug resistance. The development for use as anti-tumor agents of compounds that directly inhibit the kinase activity of the EGFR, as well as antibodies that reduce EGFR kinase activity by blocking EGFR activation, are areas of intense research effort (de Bono J. S, and Rowinsky, E. K. (2002) Trends in Mol. Medicine. 8:S19-S26; Dancey, J. and Sausville, E. A. (2003) Nature Rev. Drug Discovery 2:92-313). Several studies have demonstrated or disclosed that some EGFR kinase inhibitors can improve tumor cell or neoplasia killing when used in combination with certain other anti-cancer or chemotherapeutic agents or treatments (e.g. Raben, D. et al. (2002) Semin. Oncol. 29:37-46; Herbst, R. S. et al. (2001) Expert Opin. Biol. Ther. 1:719-732; Magne, N et al. (2003) Clin. Can. Res. 9:4735-4732; Magne, N. et al. (2002) British Journal of Cancer 86:819-827; Torrance, C. J. et al. (2000) Nature Med. 6:1024-1028; Gupta, R. A. and DuBois, R. N. (2000) Nature Med. 6:974-975; Tortora, et al. (2003) Clin. Cancer Res. 9:1566-1572; Solomon, B. et al (2003) Int. J. Radiat. Oncol. Biol. Phys. 55:713-723; Krishnan, S. et al. (2003) Frontiers in Bioscience 8, e1-13; Huang, S et al. (1999) Cancer Res. 59:1935-1940; Contessa, J. N. et al. (1999) Clin. Cancer Res. 5:405-411; Li, M. et al. Clin. (2002) Cancer Res. 8:3570-3578; Ciardiello, F. et al. (2003) Clin. Cancer Res. 9:1546-1556; Ciardiello, F. et al. (2000) Clin. Cancer Res. 6:3739-3747; Grunwald, V. and Hidalgo, M. (2003) J. Nat. Cancer Inst. 95:851-867; Seymour L. (2003) Current Opin. Investig. Drugs 4(6):658-666; Khalil, M. Y. et al. (2003) Expert Rev. Anticancer Ther. 3:367-380; Bulgaru, A. M. et al. (2003) Expert Rev. Anticancer Ther. 3:269-279; Dancey, J. and Sausville, E. A. (2003) Nature Rev. Drug Discovery 2:92-313; Kim, E. S. et al. (2001) Current Opinion Oncol. 13:506-513; Arteaga, C. L. and Johnson, D. H. (2001) Current Opinion Oncol. 13:491-498; Ciardiello, F. et al. (2000) Clin. Cancer Res. 6:2053-2063; Patent Publication Nos: US 2003/0108545; US 2002/0076408; and US 2003/0157104; and International Patent Publication Nos: WO 99/60023; WO 01/12227; WO 02/055106; WO 03/088971; WO 01/34574; WO 01/76586; WO 02/05791; and WO 02/089842).
An anti-neoplastic drug would ideally kill cancer cells selectively, with a wide therapeutic index relative to its toxicity towards non-malignant cells. It would also retain its efficacy against malignant cells, even after prolonged exposure to the drug. Unfortunately, none of the current chemotherapies possess such an ideal profile. Instead, most possess very narrow therapeutic indexes. Furthermore, cancerous cells exposed to slightly sub-lethal concentrations of a chemotherapeutic agent will very often develop resistance to such an agent, and quite often cross-resistance to several other antineoplastic agents as well.
Thus, there is a need for more efficacious treatment for neoplasia and other proliferative disorders. Strategies for enhancing the therapeutic efficacy of existing drugs have involved changes in the schedule for their administration, and also their use in combination with other anticancer or biochemical modulating agents. Combination therapy is well known as a method that can result in greater efficacy and diminished side effects relative to the use of the therapeutically relevant dose of each agent alone. In some cases, the efficacy of the drug combination is additive (the efficacy of the combination is approximately equal to the sum of the effects of each drug alone), but in other cases the effect is synergistic (the efficacy of the combination is greater than the sum of the effects of each drug given alone). For example, when combined with 5-FU and leucovorin, oxaliplatin exhibits response rates of 25-40% as first-line treatment for colorectal cancer (Raymond, E. et al. (1998) Semin Oncol. 25(2 Suppl. 5):4-12).
Growth factors acting through receptor tyrosine kinases (RTKs) drive tumor initiation and progression by accelerating cell proliferation and promoting cell survival. The RTKs for epidermal growth factor (EGF) and insulin-like growth factor (IGF) contribute to tumorigenesis for a multitude of tumor types including non-small cell lung cancer (NSCLC), colorectal, pancreatic, and breast tumors (Holbro, T., and Hynes, N. E. (2004). ErbB receptors: directing key signaling networks throughout life. Annu Rev Pharmacol Toxicol 44, 195-217; Kurmasheva, R. T., and Houghton, P. J. (2006). IGF-I mediated survival pathways in normal and malignant cells. Biochim Biophys Acta 1766, 1-22; Levitzki, A. (2003). EGF receptor as a therapeutic target. Lung Cancer 41 Suppl 1, S9-14; Roskoski, R., Jr. (2004). The ErbB/HER receptor protein-tyrosine kinases and cancer. Biochem Biophys Res Commun 319, 1-11.) Tumor cells can exhibit redundancy surrounding RTKs that contributes to de novo resistance to a single RTK inhibitor, and crosstalk between RTKs can confer acquired resistance whereby the inhibition of one RTK is compensated by enhanced activity through an alternative RTK. It has been shown that IGF-1R signaling is associated with acquired resistance of cancer cells to chemo or radiation therapies, and molecular targeted therapies including epidermal growth factor receptor (EGFR) inhibition. Indeed, it has recently been shown that in several different cancer types the efficacy of EGFR and ErbB2 signal transduction inhibitors could be acutely attenuated by IGF-1R activation of the PI3-kinase/Akt pathway (Chakravarti, A., Loeffler, J. S., and Dyson, N.J. (2002). Insulin-like growth factor receptor I mediates resistance to anti-epidermal growth factor receptor therapy in primary human glioblastoma cells through continued activation of phosphoinositide 3-kinase signaling. Cancer research 62, 200-207; Jones, H. E., Goddard, L., Gee, J. M., Hiscox, S., Rubini, M., Barrow, D., Knowlden, J. M., Williams, S., Wakeling, A. E., and Nicholson, R. I. (2004). Insulin-like growth factor-I receptor signaling and acquired resistance to gefitinib (ZD1839; Iressa) in human breast and prostate cancer cells. Endocr Relat Cancer 11, 793-814; Lu, Y., Zi, X., Zhao, Y., Mascarenhas, D., and Pollak, M. (2001). Insulin-like growth factor-I receptor signaling and resistance to trastuzumab (Herceptin). Journal of the National Cancer Institute 93, 1852-1857; Nahta, R., Yuan, L. X., Zhang, B., Kobayashi, R., and Esteva, F. J. (2005). Insulin-like growth factor-I receptor/human epidermal growth factor receptor 2 heterodimerization contributes to trastuzumab resistance of breast cancer cells. Cancer research 65, 11118-11128). For instance, IGF-1R activation correlates with acquired resistance of breast and prostate cancer cells to EGFR inhibition (Jones et al., 2004). IGF-IR has also been shown to mediate resistanceto anti-EGFR therapies in glioblastoma, colorectal, and NSCLC tumor cells (Chakravarti et al., 2002; Liu et al., 2001; Jones et al., 2004; Morgillo et al., 2006; Hurbin et al., 2003; Knowiden et al., 2005).
US2006/0235031 refers to 6,6-bicyclic ring substituted heterobicyclic protein kinase inhibitors as IFG1R inhibitors and uses thereof, including for treating cancer. Valeriote et al., Cancer Chemotherapy Reports, 59(5), 895-900 (1975), states that “extensive literature describing additivity and synergism in anticancer agents exists.” US2003/0114467; US2003/0153752; and US2005/0037999 refer to pyrazolo- and pyrrolo-pyrimidines and uses thereof, including for cancer treatment, and generally refer to various combinations with other anticancer agents. US2005/0153966 refers to heterocyclic compounds said to be kinase inhibitors and uses thereof, including for cancer treatment. US2004/0180911 refers to pyrimidine derivatives and uses thereof, including for tumors and proliferative diseases, and states that the compounds can be used in combination with other chemotherapy drugs. WO2004/056830 refers to pyrrolopyrimidine derivatives and uses thereof, including for cancer treatment, and states that the compounds can be used in combination with other anticancer agents. US2004/0106605 is entitled “Synergistic Methods and Compositions for Treating Cancer,” and generally refers to combinations of IGF1R inhibitors with EGFR inhibitors.